A new, highly compliant vascular graft fabricated from a unique polyurethane material will be developed and tested. The bulk and surface properties required of this material have been decoupled and developed independently in two separate materials. The final polymer will possess overall optimized characteristics by blending optimized surface active copolymers into the optimized bulk material. Using a patented process for fabrication of multi-layered tubing, 4 mm diameter vascular grafts will be produced. These grafts will be tested both in vivo and in vitro. In vitro testing will include compliance, burst strength, kink radius, elongation and suture pullout strength. In vivo evaluation will be accomplished by implanting 8 cm lengths in the carotid arteries of mature goats. These will be checked for patency every 30 days using 99m Technetium scanning. After 60 days of observation, grafts will be explanted and resubjected to the in vitro test protocol. Additionally, both SEM and standard microscopic examinations will be performed.